1. Field of the Invention
This invention relates to a photosensitive resin composition useful for forming protective films such as insulating protective films for use in semiconductor devices, orientation films for use in liquid crystal display devices, and insulating films for use in multi-layered printed circuit boards, and to a process for forming a patterned polyimide film using said composition.
2. Description of the Prior Art
As conventional heat resistant photosensitive materials, there are known, for example, a material comprised of polyamic acid and bichromic acid salt (Japanese Patent Publication (Kokoku) No. 49-17374 corresponding to USP 3,623,870, GB 1316976 and CA 918484), a material prepared by introducing a photosensitive group into the carboxyl group of polyamic acid with the aid of an ester bond (Japanese Pre-examination Patent Publication (Kokai) No. 49-115541 and Japanese Pre-examination Patent Publication (Kokai) No. 55-45746, which correspond to USP 3,957,512 and GB 1467226), a material comprised of polyamic acid and an amine compound having a photosensitive group (Japanese Pre-examination Patent Publication (Kokai) No. 54-145794 corresponding to U.S. Pat. No. 4,243,743), and a material prepared by introducing a photosensitive group into the carboxyl group of polyamic acid with the aid of a silyl ester bond (Japanese Pre-examination Patent Publication (Kokai) No. 62-275129).
These photosensitive materials, however, are required to use, as a liquid developer, an organic solvent when forming a pattern. The use of the organic solvent involves the problems such as an affect on the operator's health and the treatment of waste liquids.
In order to solve the above problems, there have been proposed as a photosensitive material capable of developing with an aqueous liquid, for example, a material comprised of a substance prepared by introducing a photosensitive group into the carboxyl group of polyamic acid with the aid of an amido bond (Japanese Pre-examination Patent Publication (Kokai) No. 60-100143 and Japanese Pre-examination Patent Publication (Kokai) No. 2-157845, which correspond to U.S. Pat. No. 4,515,887, U.S. Pat. No. 4,587,204 and GB 2145728), a positive type photosensitive composition prepared by mixing a polyimide resin having a phenol group with naphthoquinonediazidosulfonic acid ester (Polymer Engineering and Science, July 1989, Vol. 29, 954).
These photosensitive materials, however, involve the problems that they require a long time to develop and can not exhibit a sufficient sensitivity especially when formed into a thick film.